The present invention relates to a device for detecting the focal deviation value for the focusing of an optical apparatus that may be employed in automatic focusing of a camera.
There has been a growing need for incorporating automatic focusing capabilities in optical apparatus such as cameras, and in particular, video cameras. In one approach to automatic focusing, a beam of infrared light is used to detect the distance to the object and the camera is automatically adjusted to be in focus. This "active" system has long been used with commercial cameras but it suffers from such disadvantages as limited distances that can be detected and fairly large power consumption. Under these circumstances, a "passive" system is considered to hold much promise in future applications, and efforts to commercialize this system have been started. Basically, this "passive" system consists of examining the image of the object, detecting either the distance to the object on the basis of such a factor as parallax or the deviation from the proper focus position of the image, and automatically adjusting the camera to be in focus on the basis of the detected value. The present invention relates to the technique for implementing the "passive system".